U.S. Pat. No. 6,232,672 discloses a handheld work apparatus whose drive motor drives a generator. The generator supplies the power for operating a first electrical load such as a heater unit. The generator power generated varies in dependence on the rotational speed. At low rotational speeds only small amounts of power are available, at high rotational speeds, however, large amounts of power are available. The heating element here is configured so that a sufficient heating can he achieved at high rotational speeds, in order to, for example in the case of a carburetor heater, avoid the freezing of atmospheric moisture from the surroundings on the housing of the carburetor. Thereby it must be ensured that no overheating of the carburetor takes place because an overheating in the case of a carburetor heater can lead to the formation of vapor bubbles in the fuel and thus lead to an unstable operating performance of the combustion engine.
For controlling the heating power of a carburetor heater, it is suggested according to U.S. Pat. No. 7,816,796 to regulate the heating power of a heater unit in dependence on the rotational speed of the combustion engine. For this, a control unit is provided which controls the supplied heating energy in dependence on the rotational speed of the combustion engine.
If a carburetor heater is optimally configured with such a control unit, a disruption-free preparation of the mixture and thus a secure operation of the combustion engine can be ensured even at low ambient temperatures.
If further heater units are switched on in addition to the carburetor heater, for example handle heaters, the voltage at the carburetor heater drops because the generator can only provide limited electrical power. The drop in the voltage at the carburetor heater can result in a temperature drop.